Darwin: Better battery indication #718

Job	Run time
pkgs-linux: nixpkgs: build	3m 31s
pkgs-linux: nixpkgs: prebuilt	6m 49s
pkgs-linux: haskell-nix: build	2m 29s
pkgs-linux: haskell-nix: prebuilt	2m 30s
pkgs-linux: shajra: build	3m 9s
pkgs-linux: shajra: prebuilt	2m 26s
installers-linux	8m 57s
pkgs-darwin: nixpkgs: build	7m 46s
pkgs-darwin: nixpkgs: prebuilt	7m 59s
pkgs-darwin: haskell-nix: build	4m 53s
pkgs-darwin: haskell-nix: prebuilt	7m 4s
pkgs-darwin: shajra: build	3m 32s
pkgs-darwin: shajra: prebuilt	4m 23s
	1h 5m 28s

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